Outcrossed Lam^P escapers are slower to right themselves than controls. Heterozygous adults are indistinguishable from controls.

Lam^P homozygous and heterozygous mutants exhibit lower pupariation height, indicative of reduced larval locomotion and negative gravitaxis.

65% of Lam^P homozygotes and 45% of Lam¹⁴/Lam^P transheterozygotes eclose. Resulting adults show defects in walking and flying.

Homozygotes have a prolonged developmental time course, with a delay of up to 3 days at 24^oC. Only 5-10% of homozygotes survive until adulthood, with survival rate being inversely correlated with population density. There are three major periods of homozygous lethality; including the embryonic stages (20-30% lethality), the pupal stages (50-60% lethality), and the eclosion of the adult fly (5-10% lethality). Adults die within two weeks of eclosion. Homozygous adults are sterile. Females have abnormal ovaries, with a reduced number of ovarioles. Late stages of oogenesis are rarely detected, and oocytes are shorter than normal. Male gonads have no gross morphological defects, but there is a drastic reduction or complete loss of sperm motility. Homozygous adults are unable to fly, move more slowly than wild-type flies, and display "spastic" behaviour after losing motor coordination. Homozygous adults take on average several minutes to right themselves (returning to an upright posture from a dorsal position), in contrast to heterozygous and wild-type adults who right themselves immediately. Ultrastructural analysis of the heads of homozygous adults reveals clustering of nuclear pore complexes in the nuclear membrane, a high incidence of annulate lamellae (stacked sheets of membranes in the cytoplasm containing a high density of pore complexes, which are often continuous with the rough endoplasmic reticulum), and a partial of complete loss of the nuclear envelope.

The few surviving adults show reduced viability combined with locomotion ataxy. They cannot fly and walking is difficult. Males and females are sterile.